Downhole expandable casting hanger

Abstract

A hanger assembly 10 for suspending an inner pipe string 32 within an outer casing 16 from a particular location therein. The hanger assembly includes a hanger body 30 and an expandable locking assembly 46 comprised of a plurality of latching fingers 77 secured at their lower ends about the hanger body by a split retainer ring 48 which permits limited pivotal movement of the latching fingers about their lower ends. Each latching finger 47 is provided with a hook surface 71 adjacent its upper end adapted to engage an upward facing abutment 20 on the inner profile of the outer casing. The free ends of the latching fingers are urged outwardly by a circular spring 58. The retainer 48 and locking assembly 46 are secured to the hanger body 30 by a connecting shear ring 55 which restrains relative axial movement of the locking assembly on the hanger body until the latching fingers hook on the inner profile of the outer casing whereby the shear ring 55 is parted by a predetermined weight of the inner pipe string and the hanger body 30 slides downward to lock the fingers 47 in latched relation with the outer casing 16. By uplifting the hanger 30, cooperating cam surfaces 72, 75, 19, 26 on the fingers 47 and outer casing 16 permit extraction of the inner pipe string 32 if desired.

What is claimed is: 
     
       1. A hanger assembly for suspending an inner pipe string within and from an outer casing comprising: an elongated tubular hanger body with one end adapted for releasable connection to a well tool and the other end adapted as a lower end for connection to an inner pipe string;   said hanger body having a recessed exterior surface portion intermediate its ends and an enlarged diameter locking surface superjacent said recessed portion;   a locking assembly sleeved around the recessed surface portion of the hanger body, said locking assembly being comprised of a plurality of longitudinally extending latching fingers arranged circumferentially about the hanger body, said locking assembly including a retainer ring divided into a pair of semi-circular elements arranged in co-planar circumferential relation around the hanger body and about the lower ends of the latching fingers;   cooperative means on said semi-circular retainer elements and said latching fingers for mounting the latching fingers to the hanger body for limited pivotal movement about their lower ends,   means for connecting said semi-circular retainer elements to the hanger body whereby said locking assembly is connected to the hanger body;   means for continually and yieldably urging the free ends of the latching fingers away from the hanger body whereby said locking assembly is continually biased toward an expanded condition;   said means for continually and yieldably urging the free ends of the latching fingers comprises a split circular spring carried on the inner surfaces of each of the latching fingers to urge pivoted movement of the latching fingers about their lower ends;   a downward facing stop surface provided on each said latching finger adjacent the upper free end thereof whereby when said hanger assembly with a pipe string suspended therefrom is lowered into an outer casing string, the latching fingers of the locking assembly are adapted to expand outwardly at their free ends in pivotal movement about their lower ends whereby the stop surfaces thereon are adapted to engage a mating surface formed in the inner profile of a segment of the outer casing string and arrest further downward movement of the hanger assembly; and   shear means for restraining relative axial movement of the locking assembly on said hanger body until the stop surfaces of the latching fingers engage said mating surfaces of the outer casing string whereby the shear means for restraining relative axial movement is adapted to be shorn by a predetermined weight of the pipe string to permit relative sliding movement between the latching fingers and the hanger body whereby the locking surface holds the upper ends of the latching fingers in expanded latched relation with the outer casing and prevents inward movement of the upper ends of the latching fingers.   
     
     
       2. A hanger assembly as set forth in claim 1 wherein each of said latching fingers is provided on its outer facing surface with an enlarged hook portion adjacent its upper end, said hook portion defining a downwardly facing abutment adapted to engage an upwardly facing abutment on the inner profile of the outer casing. 
     
     
       3. A hanger assembly as set forth in claim 1 further including cam surfaces on the exteriors of said latching fingers cooperable with mating cam surfaces provided on the inner profile of the outer casing as an upward lifting force is applied to the hanger body to thereby force the latching fingers to retracted collapsed condition against the hanger body whereby the hanger assembly and pipe string suspended therefrom may be withdrawn from the outer casing string. 
     
     
       4. A hanger assembly for suspending an inner pipe string within and from an outer casing comprising: an elongated tubular hanger body with one end adapted for releasable connection to a well tool and the other end adapted as a lower end for connection to an inner pipe string;   said hanger body having a recessed exterior surface portion intermediate its ends and provided with external screw threads subjacent said recessed portion and an enlarged diameter locking surface superjacent said recessed portion;   a locking assembly sleeved around the recessed surface portion of the hanger body, said locking assembly being comprised of a plurality of longitudinally extending latching fingers arranged circumferentially about the hanger body, said locking assembly including a retainer ring divided into a pair of semi-circular elements arranged in co-planar circumferential relation around the hanger body and about the lower ends of the latching fingers;   cooperative means on said semi-circular retainer elements and said latching fingers for mounting the latching fingers to the hanger body for limited pivotal movement throughout a limited angle of movement about their lower ends, each said semi-circular retainer element being provided with external threads corresponding to those provided on the exterior of the hanger body subjacent its recessed surface portion;   a connecting ring having internal threads cooperatively engaged with the external threads of the semi-circular retainer elements and the external threads of the hanger body subjacent its recessed surface portion whereby the connecting ring connects the locking assembly to the hanger body;   means for continually and yieldably urging the free ends of the latching fingers away from the hanger body whereby said locking assembly is continually biased toward an expanded condition;   said means for continually and yieldably urging the free ends of the latching fingers comprises a split circular spring carried on the inner surfaces of each of the latching fingers to urge pivotal movement of the latching fingers about their lower end;   a downward facing stop surface provided on each said latching finger adjacent the upper free end thereof whereby when said hanger assembly with a pipe string suspended therefrom is lowered into an outer casing string, the latching fingers of the locking assembly are adapted to expand outwardly at their free ends in pivotal movement about their lower ends whereby the stop surfaces theron are adapted to engage a mating surface formed in the inner profile of a segment of the outer casing string and arrest further downward movement of the hanger assembly, said connecting ring having a weakened portion whereby said ring is adapted to fail at said weakened portion from the weight of the inner pipe string to permit relative sliding movement between the latching fingers and the hanger body whereby the locking surface holds the upper ends of the latching fingers in expanded latched relation with the outer casing and prevents inward movement of the upper ends of the latching fingers.   
     
     
       5. A hanger assembly as set forth in claim 4 wherein each latching finger is provided with an outwardly projecting boss at its lower end, said semi-circular elements are each provided with a groove extending throughout its semi-circular internal surface and the bosses of the plurality of latching fingers are received in the semi-circular grooves of the semi-circular retainer elements, the lower end of each said latching finger being defined by an upwardly and outwardly inclined surface and the semi-circular retainer elements being each provided above its internal groove with an upward facing tapered surface whereby each latching finger is adapted for limited pivotal movement about its lower end.   
     
     
       6. A hanger assembly as set forth in claim 4 wherein each of said latching fingers is provided on its outer facing surface with an enlarged hook portion adjacent its upper end, said hook portion defining a downwardly facing abutment adapted to engage an upwardly facing abutment on the inner profile of the outer casing.